Conversions of hydrocarbons



April 30, 1946., v. HAENSEL ETAL 2,399,224

CONVERSIONS OF'H-YDROGARBONS Filed Dec. 2e, 1942 je/Udjra Z222 Zofze w i Jejvarzzz'alz Zone f6' Patented Apr. 30, 1946 UNITED STATES PATENT maar GFFICE ooNvERsioNs oF HYDaooAReoNs Ware Application December 26, 1942, Serial No. 470,221

9 Claims.

This invention relates particularly to an improved process for reducing the bromine number of gasolines containing unsaturated hydrocarbons. Cracked or reformed gasolines, although having a relatively high initial octane number, are usually unsuitable for use in aviation fuel because of th'eir high olefin content and relatively low lead susceptibility. The present invention is directed to an improved method of reducing the bromine number of such gasolines.

The bromine number of unsaturated gasolines may be reduced to less than half, with a resultant increase in lead susceptibility, by contacting the gasoline with certain catalysts under specific conditions of operation. One suitable method, which we have previously disclosed, is treating the gasoline with an acid-acting oxygen compound of phosphorus at a temperature of from about 250 F. to about 750 F. and preferably of from about 350 F. to about 600 F. under suicientpressure to maintain at least a substantial portion of the material in the reaction zone at the conditions of operation in liquid phase. Such process is usually conducted at a space velocity of from about 0.5 to about 10, the space velocity being defined as the weight of charge per hour per unit Weight of catalyst in the reaction zone. Satisfactory but not necessarily equivalent catalysts include orthophosphoric acid, pyro-phosph'oric acid, copper pyro-phosphate, cadmium pyro-phosphate, etc. which may be employed either alone or in admixture with a suitable supporting material, such as kieselguhr, pumice, bentonite, bauxite, and other siliceous and aluminiferous materials.

Another suitable method of operation is to subject the gasoline to contact with' a silica base catalyst under selected conditions of operation. The silica base catalysts comprise various associations of silica with one or more compounds of elements whose oxides are refractory, such as alumina, zirconia, magnesia, thoria, ceria, etc. These catalysts may be synthetically prepared. Certain natural occurring materials, such as bentonite, montmorillonite, oridin, etc. may be used but not necessarily with equivalent results. These catalysts are usually employed at a temperature of below 1000 F. and more generally at a temperature of below 900 F., and in one method of operation are used at a temperature of between about 400 F. and about 700 F. under sucient pressure to maintain at least a substantial portion of the material in the reaction zone in `liquid phase. The weight space velocities in this method of operation will ordinarily be within the range of from about 0.3 to about 15.

We have now found that improved results in the foregoing general processes may be obtained by subjecting the gasoline to a two-stage treatment, that is, subjecting the heavier and lighter fractions of the gasoline to treatment under different conditions of operation. This improved process may be conducted by rst separating the gasoline intolight and heavy fractions and then subjecting each fraction to separate treatment with the catalyst under different conditions of operation, followed by blending of the desired gasoline fractions. In another method of operation the full boiling range gasoline may be subjected to treatment with the catalyst, the resultant products separatedv into light and heavy fractions, the heavy fractions subjected to a separate treatment in the presence of a catalyst under more severe conditions of operation, and blending of the desired fractions of th'e products of both steps of the process. V

The exact reasons for the improved results obtained by the two-stage process of the present invention are not completely known, but it is be-` lieved that the olens present in the lower boiling fraction of the gasoline are in part transformed into higherboiling hydrocarbons. If a. higher temperature is used originally in the treatment of the full boiling range gasoline, th'e carbon formation is excessive and may negative the commercial importance of the process. On the other hand, if the full boiling range gasoline charging stock is given a second treatment at the higher temperatures the lower boiling saturated hydrocarbon has a dilution effect. In addition, it is de-.` sired in most cases to maintain a liquid phase in the reaction Zone since our experiments have indicated that'considerably less carbon formation occurs with liquid phase operations as compared to vapor phase operations. The presence of large amounts of lighter hydrocarbons preclude the treatment of the charging stock in liquid phase at the higher temperatures.

Thus,v the present invention offers an improved process for reducing the bromine number of unsaturated cracked gasolines with increased yield, lower bromine number, and less carbon formation than is otherwise obtainable.

In one specific embodiment, the present invention relates to a process for reducing the bromine number of an unsaturated cracked gasoline which comprises separating said gasoline into a light fraction and a heavy fraction, subjecting the light fraction to contact with a suitable catalyst at a temperature of from about 400 `rito about 550 F. under suflicent pressure to maintain at uct having a bromine number of less than half that of said unsaturated cracked gasoline.

In another specic embodiment, the invention*V relates to a process for reducing the bromine number of an unsaturated cracked gasoline which comprises subjecting said gasoline to treatment with a suitable catalyst at a temperature of from about 400 F. to about 550 F. under sufficient pressure to maintain at least a portion of the hydrocarbons in the reaction zone in liquid phase, separating the resultant products into light and heavy gasoline fractions, subjecting said heavy fraction to separate treatment with av suitable catalyst at a temperature of from about 480 F. to about '700 F. under sufficient pressure to maintain at least a portion of the hydrocarbons in the reaction zone in liquid phase, separating material boiling within the desired range from the products of both reactions, and blending regulated amounts thereof to produce a final product having a bromine number of less than half that of said unsaturated cracked gasoline.

Y The invention will be further. explained in connection with the accompanying flow diagram; matic drawing which illustrates several manners in which the process may be conducted.

The invention is described in conjunction with a cracking operation which may be either catalytic or noncatalytic. If aviation gasoline is desired as the nal product of the process and the charging stock to the process Vcomprises a material boiling above the range of gasoline, it is usually preferred that the cracking step be catalytic. It is understood that, instead of cracking, a reforming operation may be utilized when the charging stock of the process is a material boiling substantially within the range of gasoline, and the reforming operation may be either catalytic or non-catalytic.

Referring to the drawing, the charging stock is introduced to the process through line I and may be commingled with certain recycle streams in a manner to be hereinafter described in detail, and the commingled material is supplied to cracking zone 2. Any suitable cracking or reforming process and any suitable cracking or reforming catalyst, when employed, may be utilized in zone 2.

The cracked products are directed through line 3 intoseparation zone 4. This separation zone may comprise one or a plurality of suitable flashing, fractionating, absorbing, or stripping zones, whereby the products introduced thereto may be separated into the desired fractions. Material boiling above the range of gasoline alone or, in certain cases, together with higher boiling gasoline fractions such as those boiling above 300 or 350 F., areV withdrawn from the lower portion of zone 4 through line 5 and may be removed from the process. Preferably, however, at least a portion of this material is recycled by way of lines 6 and I to zone 2 for further conversion therein. Process gases, which may or may not include butane, as desired, are Withdrawn from zone 4 through line 'I to storage or further treatment, as desired.

The desired gasoline fraction is withdrawn from zone 4 through line 8 and, in one specific embodiment of the invention, is directed into separation zone 9. Separation zone 9 may likewise be of any suitable form in order to effect the separation of the gasoline introduced thereto into light and heavy fractions. The light gasoline fraction will usually have an end-boiling point within the range of from about to about 225 F. and the heavy fraction will contain material boiling above this range. The heavy fraction may have an end-boiling point within the range of from 300 to 350 F. more or less.

The light fraction is withdrawn from zone 9 through line I0 and is directed through line il into deolenation zone I2. The term deolefination as used in the present specication and claims is intended broadly to define the process heretofore described; namely, the reaction or, more accurately, the series of reactions which occur in forming a liquid product, a substantial portion of which boils within the range of the unsaturated gasolines supplied as charging stocks to zones I2 and 20 and has a bromine number substantially lower than that of said charging stocks.

Zone I2 may comprise any suitable apparatus whereby the material introduced thereto may be intimately contacted with the` catalyst underthe desired conditions of operation. The catalyst maybe employed either in the form of granules, pellets, or otherfpreformed shapes, or in the form of `finely divided powder. The conditions of operation are, as previously mentioned, from about 400 to about 550Y F. and preferably from about 4509 to about 500 F. and suiiicient pres-A sure to maintain at least a portion of the hydrocarbons in the reaction zone in liquid phase. The pressure employed will usually be within the range of from about 200 to about 1000 pounds, or more, per square inch.

YThe products from deolefination zone I2 are directed through line I3 into separation zone I4, which likewise may be of any suitable form in order to eiect the separation of the products introduced thereto into the desired fractions. In

the preferred operation of zone I2, there will beV substantially little cracking and therefore almost no gas for separation in zone I4.' However, if any gas is formed, the same may be removed by well known means not illustrated. The products in zone I4 are separated into a light gasoline fraction, a heavy gasoline fraction, and any higher boiling material formed during the reaction. The

light gasoline fraction is withdrawn from zoneV I4 through line I5 for blending in a manner to be subsequently described, The material boiling above the range of the desired gasoline product may be withdrawn from zone I4 through-line gasoline fraction previously separated in zone 8 is withdrawn therefrom through line 2i and is preferably directed through line I9 into zone 20 forV conversion therein in commingled state with the heavy gasoline fraction withdrawn through line I8 from zone I4, i

Deolefination zone 20 will be similar 'to zone I2 and may employ either the same type or a different type of the catalysts heretofore mentioned. In this case, however, the temperature employed is higher than that utilized in zone 2l, and the temperature in zone 20 may thus be within the range of from about 480 to about 700 F. and preferably is within the range of from about 500 to about 600 F. Sufficient pressure is preferably utilizedV to maintain at leasta portion of the hydrocarbonsin the reaction zone in liquid phase, and this pressure may, in general, range from about 400 to about 1000 pounds per square inch or more.

The products from zone 20 are direoted'through line 22 into separation zone 23. Zone 23 may be similar to the previously described separation zones and should be of suitable form to effect the desired separation of the products, which in this case will comprise the separation of a gasoline fraction having the desired end-boiling point from higher boiling material. The gasoline having the desired end-boiling point is withdrawn from zone 23 through line 24 and is commingled with the light gasoline fraction previously separated in zone I4 and withdrawn therefrom through line I5. This material h-asa relatively high initial octane number and now has a reduced bromne number and improved lead susceptibility so that, upon the addition of the required amount of tetraethyl lead, a final product is obtained which, is particularly suitable for use in aviation fuel, e

The higher boiling products separated in zone 23 may be withdrawn therefrom through line 25 and may be removed from the process, but preierably at least a portion thereof is directed through lines 26 and I to zone 2 for further conversion therein.

The heretofore described specific embodiment of the invention is an operation in which the cracked gasoline is separated into light and heavy fractions prior to the deolenation treatment. The following description covers a process in which the cracked gasoline is subjected to deolefination treatment and the resultant products are fractionated into light and heavy gasoline fractions. The heavy gasoline fraction is then subjected to a separate deolenation treatment at a. higher temperature than that employed in the rst deolenation treatment.

Referring to the drawing, this operation may be accomplished by directing cracked gasoline of the desired boiling range, whichordinarily will have the usual initial-boiling point and an endboiling point Within the range of about 300 to about 350 F., from line 8 to line II into deoleiination zone l 2, thus bypassing separation zone 9 which may be eliminated in this embodiment of the invention. Zone I 2 will be similar to that previously described and will usually employ a temperature within the range of about 400 to about 550 F. under suiicent pressure to maintain at least a portion of the hydrocarbons in the reaction zone in liquid phase. The resultant products are then directed through line I3 into separation zone I4 wherein the desired separation, as heretofore described, is eifected. The light gasoline fraction is withdrawn from zone I4 through line I5, while the heavy gasoline fraction is directed through lines I8 and I9 into deolenation zone 20 for treatment in the manner 700v F. and preferably under sufficient pressure to .maintain at least ai portion of thehydrocarbons in the reaction zone in liquid phase. The resultant products vare directed through line 22 into zone 23, and gasoline fractions having the desired endpoint, which usually will be Within the range of about 300 to about 350 F., are withdrawn therefrom through line 24 for blending with the light gasoline fraction previously separated in zone I4 and withdrawn therefrom through line I5. The higher boiling material withdrawn through lines I6 and 25 from zones It and 23 may be removed from the process but preferably is recycled, at least in part, to zone 2 in the manner heretofore described,

As heretofore mentioned, either the same type or a `different type of Ycatalyst may be employedV infzones I2 and 20. If different type catalysts are employed in these zones, one suitable operation is to utilize the phosphoric acid type catalyst in zone I2 and to utilize thesilica base catalyst in zone 20. It is believed that this type of operation will have particularvadvantage in connection with certain types of gasolines.

`lt'rrample I Gas oil'is catalytically cracked in a fiuidized operationl in the presence of a silica-alumina type catalyst at a-temperature of 952 F. The catalytically cracked gasoline is separated into two Vfractions having the following characteristics:

The above light gasoline fraction is treated with a catalyst comprising phosphoric acid on a solid support at a temperature of 482 F. and 800 pounds per square inch to yield 66% of gasoline boiling below 200 F. and having a bromne number of 21. The above heavy gasoline fraction is treated with a similar catalyst at a temperature of 563 F. to yield 81% of gasoline boiling below 300 F. and having a bromne number of 20. The residual material boiling below 400 F. is recovered for use in motor fuel, while the residual material boiling above 400 F is recycled to the cracking zone for further conversion therein.

Upon blending of the gasoline fractions boiling below 300 F., a final product of satisfactory bromne number and satisfactory lead susceptibility is obtained, which product is suitable for use in aviation gasoline.

Example II A catalytically cracked gasoline having a 300 F. end point is treated with a silica-aluminazirconia catalyst at a temperature of 530 F. une der 800 pounds per square inch, and the products thereof are separated into a light gasoline fraction, a heavy gasoline fraction and higher boiling products. The higher boiling products are re cycled to the cracking step, while the heavy gasoline fraction is subjected to a separate treatment with a similar type catalyst ata temperature of 620 F. and under a pressure of 800 pounds per square inch. The resultant products are separated into gasoline fractions having an end point of 300 F. and higher boiling' products. The higher boiling products are recycled to the cracking zone, while the 300 F. end point gasoline is blended with the previously separated light gasoline fraction to produce a final product of satisfactory brominernumber and satisfactory lead susceptibility which is suitable for use in aviation fuel.

We claim as our invention:

1. AV process fior reducing the bromine number of olenic gasoline which comprises separating the gasoline into a light fraction and a heavy fraction, subjecting said light fraction to the action of aV phosphoric acid catalyst at a diolenation'temperature' of from about 400 F. to about 550 F., subjecting said heavy fraction to the action of a catalyst comprising silica and a refractory oxide at a Yhigher diolenation temperatm'e than the light fraction, and blending gasoline boiling products of the last-mentioned step with gasoline boiling products of the catalytic treatment of said lightl fraction.

2. The process as dened in claim 1 further characterized in that the first mentioned catalyst comprises ortho phosphoric acid.

3. The process as vdefined in claim 1 further characterized in that the'rst mentioned catalyst comprises pyro-phosphoric acid. l

4. The process asfdeiinedinclaiml 1 further characterized in that said refractory oxide comprises alumina. Y

5. 'Ihe process as defined in claim 1 further characterized in that said refractory oxide comprises zirconia.

6. The process as defined in claim 1 further characterized in that said heavy fraction is subjected to the action of the second-mentioned catalyst at a. temperature of from about 480 F. to about 700 F.

7. A hydrocarbon conversion process which `comprises subjecting an olenic distillate boiling in the gasoline range to the action of a phosphoric acid catalyst at a deolenation temperature of fromrabout 400 F. to about 550 F., separating the resultant products into a light gasoline fraction and heavier hydrocarbons, subjecting atleast a portion of said heavier hydrocarbons to the action of a catalyst comprising silica and a refractory oxide at a temperature higher than that employed in the treatment of said distillate, and blending gasoline boiling products of the last-mentioned step with at least a portion of said light gasoline fraction.

8. The process as dened in claim 7 further characterized in that said olenic distillate has an end boiling point below about 350 F.

9. The process as deiined in claim 1 further characaterized in that the products of the rstmentioned catalytic treatment are separated into light gasoline and heavier hydrocarbons and at least a portion of the latter supplied to the second-mentioned catalytic treatment.A

VLADIMR HAENSEL. VLADIMIR N. IPATLEFF. 

